In a variety of situations, it is desirable to hold a particular parameter of a system at a constant value. Depending on the nature of the system, a variety of forces can act to make the value of the parameter unstable. In order to maintain the parameter at a constant value, the system must contain active components which react to the forces causing instability in the parameter.
A common method for achieving stability in a parameter is through the incorporation of a feedback mechanism. In its simplest form, a feedback loop samples the changes occurring in the parameter and applies a counteracting force within the system to return the parameter to the desired level.
In electrical systems, a simple negative feedback loop can be achieved in a system by summing into the system a control signal whose value is inversely proportional to the difference in the value of an output signal of the system and a desired reference value of the system. Through the use of simple feedback systems, an output parameter of an electrical circuit can be made to eventually stabilize at a desired level. Also, through the use of simple feedback systems, the circuit, or any system, becomes resistant to error-inducing forces on the system.
In more complicated feedback schemes, where more than one feedback loop is operating at a time, the corrective measures implemented in the feedback loop may occasionally augment the problem. This is due to the fact that the feedback loops can often serve as catalysts for one another, and end up working against one another.
Therefore, a need has arisen for a system and method which can tune a parameter within a complex system containing more than one control loop which marshals the various control elements such that they efficiently control the parameter but do not work against one another.